There are well-known cutting tools such as inserts, drills, miniature dills, and insert type end mills. An insert is attached to a tip of a cutting tool and is used for turning, planing of iron and steel materials such as various types of steel and cast ion, or of nonferrous materials such as Al alloys or Cu alloys. A drill and a miniature drill are used for drilling, and solid type end mill are used for facing, grooving, shoulder-working. An insert type end mill is removably attached with the insert and is used for a cutting operation the same as the solid type end mill.
As the above-described coated hard metal tool, there is a well-known coated hard metal tool comprising a hard metal substrate, an adhesion bonding layer, and an amorphous carbon based lubricant coating deposited on the substrate with the adhesion bonding layer in-between, respectively constituted as follows.
(a) The hard metal substrate is composed of tungsten carbide (hereafter referred to as WC) based cemented carbide or titanium carbonitride (hereafter referred to as TiCN) based cermet.
(b) The adhesion bonding layer is formed by a sputtering apparatus using a Ti target as a cathode (evaporation source) in a reaction atmosphere comprising a mixed gas atmosphere of nitrogen and Ar or mixed gas of resolved hydrocarbon gas, nitrogen and Ar. The adhesion bonding layer consists of one or both selected from a titanium nitride layer (hereafter referred to as TN) and a titanium carbonitride (hereafter referred to as TiCN) layer and has an average thickness of 0.1 to 3 μm.(c) The amorphous carbon based lubricant coating is deposited by a sputtering apparatus using a WC target as a cathode (evaporation source) in a reaction atmosphere of a mixed gas of resolved hydrocarbon gas and Ar. The lubricant coating contains, based on an analysis using an Auger electron spectrometer,
W: 5 to 20 atomic % and
a balance consisting of carbon and unavoidable impurities, and has an average thickness of 1 to 13 μm.
Moreover, it is known that the above-described conventional type coated hard metal tool can be formed in accordance with the following steps using a deposition apparatus which is exemplified by a schematic plan view of FIG. 5A and schematic front view of FIG. 5B. The above-described hard metal substrate is placed in a deposition apparatus comprising a sputtering device equipped with a Ti target as a cathode (evaporation source), and a sputtering device equipped with a WC target as a cathode (evaporation source). While heating an interior of the apparatus, for example, at 300° C., a reaction gas is introduced into the apparatus. The reaction gas may be a mixed gas of 1 Pa, being composed of nitrogen and Ar mixed in a proportion of e.g., nitrogen flow rate: 200 sccm, and Ar flow rate: 300 sccm. Alternatively, the reaction gas may be a mixed gas of 1 Pa, being composed of resolved C2H2 gas, nitrogen, and Ar. For example, C2H2, nitrogen and Ar may be introduced into the apparatus by a proportion of C2H2 flow rate: 40 sccm, nitrogen flow rate: 200 sccm, and Ar flow rate: 300 sccm. In the reaction atmosphere, the cathode (evaporation source) of Ti target is applied with an electric power of 12 kW (frequency: 40 kHz) for sputtering, and the above-described hard metal substrate is applied with a bias voltage of e.g., −100 V. As a result an adhesion bonding layer having a predetermined thickness and comprising one or both selected from a TN layer and TiCN layer is formed by a generation of a glow discharge. Next, while maintaining the heating temperature of the interior of the apparatus at e.g., 200° C., hydrocarbons such as C2H2 and Ar in a proportion of C2H2 flow rate: 40 to 80 sccm, Ar flow rate: 250 sccm are introduced into the apparatus, thereby replacing the reaction atmosphere composed of the mixed gas of nitrogen and Ar, or the mixed gas of degraded mete, nitrogen and Ar by a reaction atmosphere of e.g., 1 Pa, being composed of a mixed gas of a resolved hydrocarbon gas and Ar. Then, the above-described hard metal substrate is applied with a bias voltage of e.g., −20V, and the WC target as a cathode (evaporation source) is applied with an electric power of output: 4 to 6 kW (frequency: 40 kHz) for sputtering. Under these conditions, an amorphous carbon based lubricant coating of a predetermined thickness is deposited on the above-described adhesion bonding layer (see Japanese Unexamined Patent Application, First Publication H07-164211, and Published Japanese translation No. 2002-513087 of PCT International Publication).
Specifically, as the above-described coated hard metal tool used for cutting of a workpiece of the above-described non-ferrous material, there is a known coated hard metal tool in which a coating comprising a hard lower layer and a lubricant upper layer is deposited on a hard metal substrate. The hard metal substrate is composed of tungsten carbide base (hereafter referred to as WC) cemented carbide or titanium carbonitride-based cermet (hereafter referred to as TiCN), and the coating has the following constitution
(a) A hard layer as the lower layer is composed of a composite nitride of Ti and Al [hereafter referred to as (Ti, Al)N] which has an average thickness of 1.5 to 10 μm and satisfies a compositional formula; (Ti1-ZAlZ)N, where Z ranges from 0.40 to 0.60 by atomic ratio.(b) An amorphous carbon based lubricant layer as the upper layer is deposited by a sputtering apparatus using a WC target as a cathode (evaporation source) in a reaction atmosphere of a mixed gas of resolved hydrocarbon gas and Ar. The amorphous carbon based lubricant layer contains, based on an analysis using an Auger electron spectrometer,
W: 5 to 20 by atomic %,
and a balance consisting of carbon and unavoidable impurities, and average thickness of 1 to 10 μm.
It is known that the (Ti, Al)N layer as the hard layer of the surface coating of the coated hard metal tool is given a high-temperature hardness, and heat resistance by the Al component, and high-temperature strength by the Ti component. By the multiplier effect of the hard layer and the coexisting lubricant upper layer of amorphous carbon, the coated cuffing tool exhibits excellent cutting performance in an operation of continuous cutting or of interrupted cutting of a workpiece such as the above-described non-ferrous material or the like.
In addition, it is known that the above-described coated hard metal tool may be produced using a deposition apparatus exemplified by a schematic explanatory view of FIG. 6 (see Published Japanese translation No. 2002-513087 of PCT International Publication). The deposition apparatus comprises an arc discharge device equipped with Ti—Al alloy of a predetermined composition as a cathode (evaporation source), and a sputtering device equipped with a WC target as a cathode (evaporation source). After placing the above-described hard metal substrate in the apparatus, the hard lower layer and the lubricant upper layer may be deposited as follows.
(a) Firstly, as the above-described lower layer, a hard layer composed of the above-described (Ti, Al)N layer is deposited on the hard metal substrate under conditions comprising: heating the interior of the apparatus at 500° C. by a heater; in that state, by a condition of e.g., electric current: 90 A, generating arc discharge between an anode and the Ti—Al alloy as the cathode (evaporation source); simultaneously, as a reaction gas, introducing nitrogen gas into the apparatus to obtain a reaction atmosphere of e.g., 2 Pa; and applying a bias voltage of e.g., −100 V to the above-described hard metal substrate.(b) Next, as an upper layer, an amorphous carbon based lubricant layer is deposited on the hard layer composed of the above-described (Ti, Al)N layer under the conditions comprising: heating the interior of the apparatus at e.g., 200° C.; introducing a mixed gas of hydrocarbon such as C2H2 or the like and Ar by a proportion of C2H2 flow rate: 40 to 80 sccm, and Ar flow rate: 250 sccm; thereby obtaining a reaction atmosphere having a pressure of e.g., 1 Pa and being composed of a mixed gas of resolved hydrocarbon gas and Ar; applying a bias voltage of e.g., −20V to the above-described hard metal substrate; and applying an electric power of output, 4 to 6 kW (frequency: 40 Hz) for sputtering to the cathode (evaporation source of the WC target).